Solve for $r$ : $\dfrac{7}{10}=r-\left(-\dfrac{8}{5}\right)$ $r =$
Explanation: To isolate $r$, we add $-\dfrac{8}{5}$ to both sides. $\begin{aligned} \dfrac{7}{10}&=r-\left(-\dfrac{8}{5}\right) \\\\ \dfrac{7}{10}{+\left(-\dfrac{8}{5}\right)}&=r-\left(-\dfrac{8}{5}\right){+\left(-\dfrac{8}{5}\right)} \\\\ \dfrac{7}{10}{+\left(-\dfrac{8}{5}\right)}&=r \end{aligned}$ Simplifying, we get: $r = -\dfrac{9}{10}$